Analog-digital converter for watt-hour meters



March 21, 1967 R. T. HOOD, JR.. ETAL 3,310,801

ANALOG-DIGITAL CONVERTER FOR WATT-HOUR METERS Original Filed Jan. 28,1963 2 Sheets-Sheet 1 March 21, 1967 r R. T. HOOD, lR.. ETALANALOG-DIGITAL CONVERTER FOR WATT-HOUR METERS 2 Sheets-Sheet 2 OriginalFiled Jan. 28, 1963 United StatesPatent Ofiice Patented Mar. 21, 1967-3,310,801 ANALOG-DIGITAL CONVERTER FOR WATT-HOUR METERS R. T. Hood,.lr., Torrance, and David R. Stuettig, Manhattan Beach, Calif.,assignors, by mesne assignments, to Hersey-Sparling Meter Company,Dedham, Mass. Continuation of application Ser. No. 254,126, Jan. 28,1963. This application May 15, 1964, Ser. No. 369,354 12 Claims. (Cl.340-347) This application is a continuation of application Ser. No.254,126, filed Jan. 28, 1963 now abandoned.

The invention relates generally to converter mechanisms of theanalog-digital type, and it relates more particularly to an improvedanalog-digital converter unit which is especially constructed to bemounted on a utility meter, such as a usual domestic watt-hour meter, soas to convert the dial indicator readings of the meter intocorresponding binary-coded digital information.

The usual domestic watt-hour meter, for example, includes a plurality ofdial indicators which indicate on a cumulative basis the consumption ofelectrical energy by the customer. The different dial indicators of themeter are used to indicate the consumption of electrical energy,

for example, on a decimal scale, and on the basis of units, tens,hundreds, and thousands of kilowatt hours.

- As is well known, other-types of utility meters, such as gas, or watermeters, also use separate dial indicators to indicate the consumption ofthe. particular commodity or energy represented by the meter. Theindication of these latter dial indicators is also made on a decimalscale, and with the various dials indicating respectively the units,tens, hundreds, and thousands digits of the reading.

An object of the present invention is to provide an improvedanalog-digital converter unit which may be conveniently coupled to theindividual dials of a utility meter, or the like, and which functions toconvert the different dial readings of the meter into equivalentbinary-coded digital signals.

The invention will be illustrated and described herein 'as applied to anelectrical power consumption watt-hour utility meter. It will be evidentas the description proceeds, however, that the unit of the invention canbe constructed to be suitable for coupling to other types of meters andmeasurement devices.

In general, the unit of the present invention is intended to be adaptedto a wide variety of applications, and to serve generally to provide aconvenient means for converting meter readings into correspondingbinary-coded signals.

Copending application Ser. No. 252,726, filed Jan. 21, 1963, describedthe system for acquiring data. In the copending case, a recording systemis described which is capable of being carried from station to stationby, for

present invention, binary-coded information is available at the variousmeters corresponding to the meter readings. It is then possible for theinspector to plug his recorder into.= convenient receptacles at thevarious meter stations, and thereby to obtain a recording inbinary-coded form of the different meter readings.

In the embodiment of the invention to be described, a separateanalog-digital code pattern is provided for each dial indicator of theutility meter on which the unit of the invention is to be mounted.Separate electrical contact brushes are also provided which selectivelyengage the different code patterns, and which are individually rotatedas the corresponding dial pointers of the utility meter rotate toindicate the consumption of energy flowing through the meter.

The brushes and code patterns of the unit of the invention areelectrically connected to an appropriate electrical receptacle, so thata binary-coded reading of the dilferent dial indicator positions of themeter may be obtained merely by plugging the above-mentioned recorder,or other suitable instrumentality, into the receptacle.

The code patterns of the unit to be described utilize a Gray code ratherthan a straight binary code. This is to minimize reading ambiguities ofthe brushes. In the straight binary code, as the count progresses fromone decimal digit to the next, it often happens that more than onebinary bit changes from 1 to O and vice versa.

Therefore, with the straight binary code, and even with the mostexacting tolerances, it is possible for the bit cross-over points in thedifferent channels of the code patterns to yield errors. By use of theGray code, as is well known, these ambiguity errors are reduced to plusor minus one decimal digit because the Gray code always changes by onlyone binary bit at'any particular point as the count progresses from onedecimal digit to the next.

It is also possible in the particular application of the analog-digitalconverter of the invention for ambiguities to exist between thedifferent dial indicators of the utility meter with which the particularunit is associated.

For example, in typical watt-hour meter, as the thousands dial pointerapproaches a whole number, the hundreds dial pointer approaches Zero. Itis therefore possible for the thousands dial pointer to reach its nextwhole number, insofar as its'equivalent binary-coded signals generatedby the unit are concerned, before the hundreds dial actually registerszero, insofar as its equivalent binarycoded signals are concerned. Thiscreates the possibility of an error of 900 kilowatt hours, for example,in the recorded reading.

The embodiment of the converter unit to be described is constructed toinclude a separate interpolation channel in each of the code patterns,and these channels are each sensed by an associated brush. The resultinginterpolation signals derived from the converter unit provide betweensuccessive dial numbers.

Another object of the invention is to provide such an improvedanalog-digital converter unit which is immune to tampering; and whichcannot be adjusted to provide spurious readings unrelated to the actualmeter readings without destroying the reading ability of the unitcompletely so that an examination of the unit obviously indicates thattampering 'has occurred.

Other objects and advantages of the invention will be come apparent froma consideration of the following description when taken in conjunctionwith the accompanying drawings, in which:

FIGURE 1 is a front elevational view of a typical dmestic watt-hourmeter, on which an analog-digital converter constructed in accordancewith one embodiment of the invention is mounted;

FIGURE 2 is a top view of the meter of FIGURE 1, and illustrates moreclearly the manner in which the con verter of the invention ismechanically coupled to the mechanism of the meter;

FIGURE 3 is an exploded view of the analog-to-digital converter assemblyof one embodiment of the invention, and illustrates the variouscomponents which make up the assembly;

FIGURE 4 is a fragmentary view of a portion of the assembly of FIGURE 3in assembled form;

FIGURE 5 is a perspective view of a rotating wiper assembly, a pluralityof which are used in the converter of FIGURE 3;

FIGURE 6 is a fragmentary sectional view of the assembly of FIGURE 5,taken substantially on the line 6-6 of FIGURE 5, and also showing themanner in which the wiper assembly of FIGURE 5 engages conductivepatterns disposed above and below the wiper assemy;

FIGURE 7 is an enlarged view of printed circuit analog-digital encoderpatterns inscribed on a supporting insulating plate or panel, a pair ofwhich are used in the assembly of FIGURE 3; and

FIGURE 8 is a representation of the Gray type binary code, which isutilized in the encoder patterns of FIG- URE 7.

As mentioned above, the improved analog-digital converter of the presentinvention is intended to be utilized in conjunction with domesticmeters, such as the watthour meter 10 of FIGURES 1 and 2.

The watt-hour meter 10 includes, as mentioned above, a plurality ofseparate dial indicators which indicate the consumption of power on adecimal scale. In the meter under consideration, for example, four suchdials are included, and these represent the power consumption on thebasis of units, tens, hundreds and thousands of decimal digits.

As best shown in FIGURE 2, the different dial indicators of the meter 10are mounted on a bracket 12. The improved analog-digital converter ofthe present invention is adapted to be conveniently mounted in the meter10, by means, for example, of a pair of screws 14 which are adapted toextend into a support 16 for the bracket 12, and which serve to mountthe converter assembly, indicated generally as 18 over the originalbracket 12 in the meter. A feature of the present invention, therefore,is that the analog-to-digital converter may be simply and easily mountedin the watt-hourv meter 10, merely by removing the glass envelope 20,and by mounting the unit of the invention over the dial indicators ofthe meter by means, for example, of the screws 14. It will beappreciated that no internal modifications, changes or adjustments ofthe meter itself are required.

It should also be reiterated that, although the improvedanalog-to-digital converter of the invention is described herein asbeing mounted on a typical domestic watt-hour consumption meter, theconverter may be mounted on any other type of meter which, for example,utilizes one or more dial indicators to indicate the amount ofconsumption of any particular commodity.

The improved analog-digital converter of the illustrated embodiment ofthe invention includes a plurality of shafts 22 (FIGURE 3). These shaftsmay be die cast, and they extend through the converter assembly toimpart rotational movement to the different components thereof, as willbe described. A corresponding plurality of cam followers 24 are mountedon the lower ends of respective ones of the shafts 22. These camfollowers 24 are in the form of individual cranks, and they may bepress-fit onto the corresponding shafts 22.

The different cam followers 24 engage the pointers of the dialindicators of the meter 10, when the converter assembly of the inventionis mounted on the meter, as shown in FIGURE 2. Therefore, as thedifferent pointers of the dial indicators rotate, they drive with themthe corresponding cam followers 24 so that equivalent respectiverotations are imparted to the different shafts 22.

The analog-to-digital converter assembly illustrated in FIGURE 3includes a lower plate, or panel 26 of a rectangular configuration, andit includes a similar upper plate or panel 28. The plates 26 and 28 areformed of insulating material. The plates are held in spaced parallelrelationship by means of a pair of spacers 30 and 32 which may becomposed, for example, of aluminum.

A further plate 34 having the same dimensions as the plates 26 and 28 isadapted to fit over the top of the plate 28. The plate 34 may be in theform of a laminated plastic sheet which is cemented over the top of theupper plate 28. The plate 34 has a plurality of dial faces inscribed onits upper surface, these dial faces corresponding to the original dialfaces of the original dial indicators of the meter 10.

The screws 14 extend through mounting holes in the plates 34, 28 and 26and down into the mount 16, the screws being held in place bycorresponding nuts 36, so that the converter assembly of FIGURE 3 isheld in an assembled condition. When the assembly is in such anassembled condition, the plates 26 and 28 are held spaced from oneanother by the spacers 30 and 32.

The shafts 22 extend through respective apertures in the plates 26 and28 and 34. Corresponding pointers 40 formed, for example, of aluminumare press-fit on the upper ends of the respective shafts 22. Thesepointers 40 cooperate with the dial calibrations on the upper surface ofthe plate 34 to provide visual indications, as shown in FIGURE 1,corresponding to the indications by the original dial indicators of themeter. These new visual indications are desired because the originaldial indicators of the meter are hidden by the assembly of theinvention.

Also mounted on the respective shafts 22 are a corresponding pluralityof wiper assemblies 42. The constructional details of the individualwiper assemblies are shown in more detail in FIGURE 5. The wiperassemblies 42 are rotated as the corresponding shafts 22 are roated. Thewiper assemblies are supported between the plates 26 and 28 bycorresponding spacers 44.

As best shown in FIGURE 7, a plurality of code patterns 46 are formed onthe upper face of the plate 26. These code patterns, as shown in FIGURE7, are composed of conductive and non-conductive segments, and they areformed on the plate 26 by any known appropriate printed circuit process.

Corresponding encoder patterns are formed on the lower surface of theplate 28, these latter encoder patterns being the mirror images of thecorresponding patterns 46 on the plate 26. The encoder patterns on thetwo plates are inter-connected in a parallel relationship so as toincrease the reliability of the unit by providing a redundancy typearrangement.

The plates 26 and 28, and the encoder patterns thereon are used forincreasing the reliability of the converter, in that each of the wiperassemblies 42 includes brushes which contact both encoder patterns onthe plates 26 and 28, so that a contact malfunction with either one ofthe patterns will not affect the operation of the assembly.

The fragmentary representation of FIGURE'4 illustrates the manner inwhich an original pointer 48 in the meter 10 engages a corresponding oneof the cam followers 24 to impart rotation to the associated drive shaft22 corresponding to rotations of the pointer 48. The drive shaft 22causes the corresponding wiper assembly 42 to cause its brushes toestablish different contact relationships with the conductive patternson the upper surface of the plate 26 and on the lower surface of theplate "50 composed, for example, of a suitable epoxy resin.

"filed Jan. 29, 1963.

28. At the same time, the corresponding pointer 40 rotates around itsscale on the top surface of the plate 34 to provide an indicationcorresponding to the original indication by the pointer 48.

As mentioned above, details of one of the rotating wiper assemblies 42is shown in FIGURE 5. The wiper assembly may include, for example, aninsulating disc A sheet of beryllium copper, or other appropriateelectrically conductive material, is bonded to the top of the assembly,and the top sheet is designated 52.

A similar sheet of beryllium copper or other suitable conductivematerial, designated 54, is bonded to the botton of the disc 50. Thesheet 52 has a plurality of teeth 56 formed in it, and these teeth arebent upwardly so as 'toengage the different segments of thecorresponding encoder pattern 58 (FIGURE 6) on the lower surface of theplate 28.

Likewise, the conductive sheet 54 has a plurality of teeth 60 formed init, and these teeth are bent downwardly to engage the correspondingencoder pattern 62 (FIG- URE 6) on the top surface of the plate 26.

The assembly of FIGURE 5 may be rhodium plated to inhibit oxidation andsimilar deterioration of the contact teeth 56 and 60. It will beappreciated that as each wiper the insulating disc 50, so as toestablish electrical contact between the conductive sheet 52 and theconductive sheet 54 which are bonded to the opposite surfaces of thedisc 50.

The printed circuit encoder patterns 62 on the top surface of the lowerplate 26 are shown in detail in FIG-' URE 7. As mentioned above, similarencoder patterns, constituting mirror images of the respective patternsof FIGURE 7, are formed on the lower surface of the upper plate 23.

The various conductive segments of each encoder pattern in FIGURE 7 isconnected to corresponding terminals, designated collectively as 70a,70b, 70c, and 70d.

These connections may be made by appropriate printed circuit conductorson theplate 26. The digital signals corresponding to the various angularpositions of the shaft 22appear acrosstheoutput terminals. These outputterminals are connected to an appropriate receptacle, such as describedin copending application Ser. No. 254,620, The receptacle is adapted toreceive a plug of a recording mechanism, so that the digital signalsappearing at the different output terminals may be recorded intherecording mechanism.

The encoder patterns of FIGURE 7 are each forme in accordance with theGray code, such as shown in FIGURE 8.

In each of the encoder patterns, the central annular conductive ring isthe common connection, and the brushes 56 of the wiper assembly 42connect the central ring to. selective ones of the outer conductiverings, in accordance with the Gray code of FIGURE 8, as thecorresponding shaft 22 is rotated.

In each of the shaft encoder patterns, the outer ring includes fivedistinct segments, and these constitute the to be attached to anon-precision meter, such absolute mechanical registry is not feasible.Therefore, in the pointer in the particular decade.

mechanism and system of the invention, electrical code logiccompensation must be employed to overcome the effects of imperfectmechanical registry or ambiguity.

Gross errors within the decades are eliminated by adopting the Graybinary code. This code, as mentioned above, changes by one bit onlybetween equivalent whole decimal numbers. The straight binary code, onthe other hand, can change by up to four bits per whole decimalincrement.

Slight misalignments of the brushes of the wiper assembly 42 can causeerrors of more than one decimal digit when the straight binary code 'isused. By contrast, when the Gray binary code is used, brush misalignmentcan normally cause no more than one decimal digit error.

The use of the Gray code reduces ambiguity to one digit in thetransition from a digit to the next highest in each decade. Thisaccuracy is not sufficientsince in'the most significant decade, forexample, a one digit ambiguity can yield an error of one thousand units.

It is fundamental that encoding errors occur in the analog-digitalmechanism described above, only near the transition from one digit tothe next highest digit in any decade. For example, a transition from anyparticular digit to the next highest in any decade, except the leastsignificant (units) decade, is accompanied by a transition from 9 to 0in the next lower decade. If imperfect angular alignment exists betweendecades inthe mechanism, it is possible for the next highest digit in aparticular decade to be reached before the previous decade has changedfrom 9 to '0. This results in one digit error in the particular decade.

The problem outlined immediately above is resolved by the logic of thehuman mind when visual readings are taken from the meter scales, such asthe scales 4%) in FIGURE 1. When visually reading the meter, thedecision in transitional cases is made on the basis of the previousdecade number, and the relative position of the to above are based onthe concept of dividing each digit into a high and a low range. Thisprovides an indication of the digit proximity range, and this indicationprovides a means for making a decision as to whether the reading of themost significant of any two decades should be increased :by one digit ordecreased by one digit within that decade.

In FIGURE 7, the interpolation conductive segments are positioned, forexample,to center on alternate digits in each decade and to extendhalfway between such alternate digits and the adjacent digits.

The object of the illustrated arrangement of interpolation segment inFIGURE 7 .is to correlate the encoded decimal digit and interpolationbit of any particular'decade to the preceding decade value. If otherthan the correct correlation is obtained, the decade being decisioned isreduced or increased by one digit. This procedure is carried out foreach successive dial indicator until all the dials have been correlated.

A system for reading the output signals from the mechanism of theinvention, after recordation by the recorder described in theafore-mentioned copending application Ser. No. 252,726, is described inthe afore-mentioned copending application Ser. No. 317,548, filed Oct.21, 1963.

The invention provides, therefore, an improved analogto-digitalconverterwhich is adapted to be mechanically coupled to a utility meter,or the like. As mentioned above, the converter of the invention isadvantageous in that it may be easily coupled to existing utility meterswithout the need to modify or change the internal mechanism of the meteritself.

The converter of the invention is' especially advantageous in that itincorporates the above-described means for eliminating ambiguity errors,so that the converter of the invention is capable of providing accurateand precise digital indications of the corresponding meter readings.

While a particular embodiment of the invention has been shown anddescribed, modifications may be made, and it is intended in the claimsto cover such modifications which fall within the spirit and scope ofthe invention.

What is claimed is:

1. An analog-digital converter unit for attachment to a multi-stageregister for encoding the digits successively represented by theindividual stages of such register into binary coded signals, saidregister having a plurality of indicating elements corresponding to therespective stages of said register, said converter unit including: asupport panel adapted to be mounted on said register over saidindicating elements, a plurality of code patterns disposed on said paneland positioned to be in axial registry with respective ones of saidindicating elements when said support panel is mounted on said register,each of said code patterns including electrically conductive segmentspositioned in a plurality of concentric annular tracks, a correspondingplurality of shafts rotatably mounted on said support panel andextending through corresponding ones of said code patterns into coupledrelationship with respective ones of said indicating elements when saidsupport panel is mounted on said register, a corresponding plurality ofelectrical contact brush members mounted on respective ones of saidshafts to be rotated thereby, each of said electrical contact brushmembers including resilient brush elements positioned to engageselectively the conductive segments in said annular tracks of respectiveones of said code patterns as said shafts rotate and to derive signalsrepresentative of successive digits from each of said code patterns,said successive digits corresponding to successive angular ranges ofeach of the respective shafts, and at least some of said code patternseach including further conductive segments arsaid code patterns, saidsuccessive decimal digits corresponding to successive angular ranges ofeach of the respective shafts, and at least some of said code patternseach including further electrically conductive segments arranged in afurther annular concentric track and indicative of whether thecorresponding shaft is in the high portion or low portion of each suchangular range, and electric cable means adapted to extend through thehousing of said utility meter and including individual conductorsconnected to the conductive segments of said code patterns.

3. An analog-digital converter unit for attachment to the decaderegister of a utility meter, or the like, for encoding the decimaldigits successively represented by the individual stages of saidregister into binary coded signals, said meter having a plurality ofindicating elements disposed in essentially coplanar relationship, saidconverter unit including: a support panel adapted to be mounted in saidmeter over said indicating elements, a plurality of code patternsdisposed in side-by-side relationship on said panel and positioned to bein axial registry with respective ones of said indicating elements whensaid support panel is mounted in said meter, each of said code patternsincluding electrically conductive segments positioned in a plurality ofconcentric annular tracks representative of Gray code binary digits, acorresponding plurality of shafts rotatably mounted on said supportpanel and extending therethrough and through the center of correspondingones of said code patterns along parallel axes essentially perpendicularto the plane of said support panel into coupled relationship withrespective ones of said indicating elements when said support panel ismounted in said meter, a corresponding plurality of electricallyconductive brush contact members mounted on respective ones of saidshafts to be rotated thereby, each of said contact members includingranged in a further annular concentric track and indicative of whetherthe corresponding shaft is in a high portion or low portion of each suchangular range.

2. An analog-digital converter unit for attachment to the decaderegister of a utility meter, or thelike, for encoding the decimal digitssuccessively represented by the individual stages of said register intobinary coded signals, said meter having a plurality of indicatingelements, said converter units including: a support panel adapted to bemounted in said meter over said indicating elements, a plurality of codepatterns disposed on said panel and positioned to be in axial registrywith respective ones of said indicating elements when said support panelis mounted in said meter, each of said code patterns includingelectrically conductive segments positioned in a plurality of concentricannular tracks, a corresponding plurality of shafts rotatably mounted onsaid support panel and extending therethrough through the center ofcorresponding ones of said code pattern into coupled relationship withrespective ones of said indicating elements When said support panel ismounted in said meter, a corresponding plurality of electrical brushcontact members mounted on respective ones of said shafts to be rotatedthereby, each of said electrical brush contact members includingresilient brush elements positioned to engage selectively the conductivesegments in said annular tracks of respective ones of said code patternsas said shafts rotate and to derive signals representative of saidsuccessive decimal digits from each of resilient brush elements incommon electrical contact with one another and positioned to engageselectively the conductive segments in said annular tracks of respectiveones of said code patterns as said shafts rotate and to derive signalsrepresentative of successive decimal digits from each of said codepatterns, said successive decimal digits corresponding to successiveangular ranges of each of the respective shafts, and at least some ofsaid code patterns each including further conductive segments arrangedin a further annular concentric track and indicative of whether thecorresponding shaft is in the high portion or low portion of each suchangular range, and electric cable means adapted to extend through thehousing of said utility meter and including individual conductorsconnected to the conductive segments of said code patterns.

4. The converter unit defined in claim 1 and which includes a pluralityof indicators mounted on respective ones of said shafts to be rotated bysaid shafts;

5. The converter unit defined in claim 1 and which includes printedcircuits formed on said support panel and interconnecting saidconductors of said cable and said conductive segments.

6. The converter unit defined in claim 1 in which said indicatingelements of said utility meter include pointers, and which includescrank-shaped cam follower members mounted on respective ones of saidshafts to engage corresponding ones of said pointers.

7. An analog-digital converter unit for attachment to a multi-stageregister for encoding the digits successively represented by theindividual stages of such register into binary coded signals, saidregister having a plurality of rotatable elements corresponding to therespective stages of said register, said converter unit including: asupport panel adapted to be mounted on said register over said rotatableelements, a plurality of code patterns disposed on said panel andpositioned to be in axial registry With respective ones of saidrotatable elements when said support panel is mounted on said register,each of said code unit and extending through corresponding ones ofsaidcode patterns into coupled relationship with respective ones of saidrotatable elements when said support panel is mounted on said register,a corresponding plurality of electrical contact brush members mounted onrespective ones of said shafts to be rotated thereby, each of saidelectrical contact brush members including resilient brush elementspositioned to engage selectively the conductive segments in said annulartracks of respective ones of said code patterns as said shafts rotateand to derive signals representative of successive digits from each ofsaid code patterns, said successive digits corresponding to successiveangular ranges of each of the respective shafts, and at least some ofsaid code patterns each including further conductive segments arrangedin a further annular concentric track and indicative of Whether thecorresponding shaft is in the high portion or low portion of each suchangular range.

8. An analog-digital converter unit for attachment to the decaderegister of a utility meter, or the like, for encoding the decimaldigits successively represented by the individual stages of saidregister into binary coded signals, said meter having a plurality ofrotatable elements, said converter units including: a support paneladapted to be mounted in said meter over said rotatable elements, aplurality of code patterns disposed on said panel and positioned to bein axial registry with respective ones of said rotatable elements whensaid support panel is mounted in said meter, each of said code patternsincluding electrically conductive segments positioned in a plurality ofconcentric annular tracks, a corresponding plurality of shafts rotatablymounted with respect to said support panel and extending therethroughthrough the center of corresponding ones of said code pattern intocoupled relationship with respective ones of said rotatable elementswhen said support panel is mounted in said meter, a correspondingplurality of electrical brush contact members mounted on'respective onesof said shafts to be rotated thereby, each of said electrical brushcontact members including resilient brush elements positioned to engageselectively the conductive segments in said annular tracks of respectiveones of said code patterns as said shafts rotate and to derive signalsrepresentative of successive decimal digits from each of said codepatterns, said successive decimal digits corresponding to successiveangular ranges of each of the respective shafts, and at least some ofsaid code patterns each including further electrically conductivesegments arranged in a further annular concentric track and indicativeof whether the corresponding shaft ,is in the high portion or loWportion of each such angular range, and electric cable means adapted toextend through the housing of said utility meter and includingindividual conductors connected to the conductive segments of said codepatterns.

9. An analog-digital converter unit for attachment to the decaderegister of a utility meter, or the like, for encoding the decimaldigits successively represented by the individual stages of saidregister into binary coded signals, said meter having a plurality ofrotatable elements disposed in essentially coplanar relationship, saidconverter unit including: a support panel adapted to be mounted in saidmeter over said rotatable elements, a plurality of code patternsdisposed in side-by-side relationship on said panel and positioned to bein axial registry with respective ones of said rotatable elements whensaid support panel is mounted in said meter, each of said code patternsincluding electrically conductive segments positioned in a plurality ofconcentric annular tracks representative of Gray code binary digits, acorresponding plurality of shafts rotatably mounted with respect to saidsupport panel and extending therethrough and through the center ofcorresponding ones of said code patterns along parallel axes essentiallyperpendicular to the plane of said support panel into coupledrelationship with respective ones of said rotatable elements when saidsupport panel is mounted in said meter, a corresponding plurality ofelectrically conductive brush contact members mounted on respective onesof said shafts to be rotated thereby, each of said contact membersincluding resilient brush elements in common electrical contact with oneanother and positioned to engage selectively the conductive segments insaid annular tracks of respective ones of said code patterns as saidshafts rotate and to derive signals representative of successive decimaldigits from each of said code patterns, said successive decimal digitscorresponding to successive angular ranges of each of the respectiveshafts, and at least some of a said code patterns each including furtherconductive seggage corresponding ones of said pointers.

11. In an analog-digital converter for a multi-stage register forencoding the digits successively represented by the individual stages ofsuch a register into binary coded signals, and said register having aplurality of rotatable elements corresponding to the respective stagesof said register, the combination of: support means mounted on saidregister over said rotatableelements, a plurality of code patternsdisposed on said supportmeans and positioned to be in axial registrywith respective ones of said rotatable elements, each of said codepatterns including segments positioned in a plurality of concentricannular tracks, a corresponding plurality of members rotatably mountedWith respect to said support means for respectively detecting saidsegments of each of said code patterns as said rotatable elements rotateand to derive signals representative of successive digits from each ofsaid code patterns, said successive digits corresponding to successiveangular ranges of each of the respective rotatable elements; and atleast one of said code patterns including further segments positioned ina further annular concentric track and indicative of Whether thecorresponding one of said rotatable elements is in the high portion orlow portion of each such range; and a corresponding plurality ofcoupling members for coupling said detecting members to respective onesof said rotatable elements.

12. In an analog-digital converter for a multi-stage register forencoding the digits successively represented by the individual stages ofsuch a register into binary coded signals and said register having aplurality of rotatable elements corresponding to the respective stagesof said register, the combination of: support means mounted on saidregister over said rotatable elements, a plurality of code patternsdisposed on said support means and positioned to be in axial registrywith respective ones of said rotatable elements, each of said codepatterns including electrically conductive segments positioned in aplurality of concentric annular tracks, a corresponding plurality ofelectrical contact brush members rotatably mounted with respect to saidsupport means, each including resilient brush elements positioned toengage selectively the electrically conductive segments in said annulartracks of respective ones of said code patterns as said rotatableelements rotate and to derive signals representative of successivedigits from each of said code patterns, said successive digitscorresponding to successive angular ranges of each of the respectiverotatable 1 1 1 2 elements, and at least one of said code patternsincluding References Cited by the Examiner further electricallyconductive segments positioned in 21 UNITED STATES PATENTS furtherannular concentric track and indicative of whether the corresponding oneof said rotatable elements in the 2818557 12/1957 p et 340 347 highportion or low portion of each such angular range; 5 10/1961 Elchacker346' 14 and a corresponding plurality of coupling members for MAYNARD RWILBUR Primar Examiner coupling said brush members to respective ones ofsaid y rotatable elements. A. L. NEWMAN, Assistant Examiner.

11. IN AN ANALOG-DIGITAL CONVERTER FOR A MULTI-STAGE REGISTER FORENCODING THE DIGITS SUCCESSIVELY REPRESENTED BY THE INDIVIDUAL STAGES OFSUCH A REGISTER INTO BINARY CODED SIGNALS, AND SAID REGISTER HAVING APLURALITY OF ROTATABLE ELEMENTS CORRESPONDING TO THE RESPECTIVE STAGESOF SAID REGISTER, THE COMBINATION OF: SUPPORT MEANS MOUNTED ON SAIDREGISTER OVER SAID ROTATABLE ELEMENTS, A PLURALITY OF CODE PATTERNSDISPOSED ON SAID SUPPORT MEANS AND POSITIONED TO BE IN AXIAL REGISTRYWITH RESPECTIVE ONES OF SAID ROTATABLE ELEMENTS, EACH OF SAID CODEPATTERNS INCLUDING SEGMENTS POSITIONED IN A PLURALITY OF CONCENTRICANNULAR TRACKS, A CORRESPONDING PLURALITY OF MEMBERS ROTATABLY MOUNTEDWITH RESPECT TO SAID SUPPORT MEANS FOR RESPECTIVELY DETECTING SAIDSEGMENTS OF EACH OF SAID CODE PATTERNS AS SAID ROTATABLE ELEMENTS ROTATEAND TO DERIVE SIGNALS REPRESENTATIVE OF SUCCESSIVE DIGITS FROM EACH OFSAID CODE PATTERNS, SAID SUCCESSIVE DIGITS CORRESPONDING TO SUCCESSIVEANGULAR RANGES OF EACH OF THE RESPECTIVE ROTATABLE ELEMENTS; AND ATLEAST ONE OF SAID CODE PATTERNS INCLUDING FURTHER SEGMENTS POSITIONED INA FURTHER ANNULAR CONCENTRIC TRACK AND INDICATIVE OF WHETHER THECORRESPONDING ONE OF SAID ROTATABLE ELEMENTS IS IN THE HIGH PORTION ORLOW PORTION OF EACH SUCH RANGE; AND A CORRESPONDING PLURALITY OFCOUPLING MEMBERS FOR COUPLING SAID DETECTING MEMBERS TO RESPECTIVE ONESOF SAID ROTATABLE ELEMENTS.